1. Field of the Invention
The present invention relates to compositions and methods for manufacture of integrated circuit systems. More particularly, organic spin-on type antireflective coating (ARC) compositions are provided that can exhibit good resistance to oxygen-based plasma etches and serve as hard masks in circuit manufacturing processes.
2. Background
In the manufacture of semiconductor devices, a variety of conductive device regions and layers are formed on the device substrate, generally segregated by electrically insulating dielectric regions. Those dielectric regions may be formed e.g. from silicon dioxide and produced by various techniques, e.g. oxide growth, sputtering or other chemical deposition procedures. In the manufacture of the device, it is necessary to make openings in the dielectric layers to permit contact and electrical communication between different regions of the device.
Photolithography is employed to form such apertures in dielectric layers. A photoresist is patterned over the dielectric layer and the dielectric regions bared upon exposure are removed by a dry etch, typically a plasma etch or ion bombardment. See generally U.S. Pat. Nos. 5,468,342 and 5,346,586.
However, resist mask also may degrade during the plasma etch of the underlying dielectric material, reducing resolution of the image patterned into the dielectric layer. Such imperfect image transfer can only compromise performance of the semiconductor device.
Certain inorganic materials known as hard masks have been interposed between dielectric and resist layers to reduce imperfections in image transfer from the resist layer to the underlying dielectric layer. The hard mask material, e.g. polysilicon, silicon nitride, aluminum, titanium silicide, or tungsten, is vapor deposited such as by sputtering onto the dielectric layer. A photoresist is then coated and imaged over the hard mask. The inorganic hard mask regions bared upon resist development are removed by a plasma etch to which the organic resist layer is resistant. Relatively high etch selectivity can be achieved between the inorganic hard mask layer and the overcoated patterned organic-based resist. Such etch selectivity is generally not possible between a dielectric layer and an organic-based resist. Upon such etching, the hard mask profile matches the resist mask. Dielectric regions exposed upon hard mask etching now can be removed by an etch that is selective for the dielectric and for which the hard mask is resistant. Because high etch selectively can be realized between the dielectric layer material and the hard mask, image transfer imperfections as discussed above can be avoided. See generally the above cited U.S. patents.
While such an approach can be effective for the manufacture of many integrated circuits, industry demands continue produce even smaller features at higher resolution.
Indeed, other problems in circuit manufacture that can limit resolution and the ability to form ever smaller features. For instance, reflection of activating radiation used to expose a photoresist can limit resolution of the image patterned in the resist. In particular, reflection of radiation from the underlying surface/photoresist interface can produce spatial variations in the radiation intensity in the photoresist, resulting in non-uniform photoresist linewidth upon development. Exposure radiation also can scatter from the underlying surface/photoresist interface into regions of the photoresist coating where exposure is not intended, again resulting in linewidth variation.
It thus would be desirable to have new compositions and methods for integrated circuit manufacture.